Furnace front wall construction for use with spreader stokers



E. c. MILLER 2,501,734 FURNACE FRONT WALL CONSTRUCTION FOR USE WITH SPREADER STOKERS 2 Sheets-Sheet 1 o o o o a c o o o o o o o o a arch 28, 1950 Filed Nov. 15, 1946 l/ n// flfl u I 5 0 6 6 2/ 2 H Fig.1

arch 28, 1950 E. c. MILLER 2,501,734

FURNACE FRONT WALL CONSTRUCTION FOR USE WITH SPREADER STOKERS Filed Nov. 15, 1946 2 Sheets-Sheet 2.

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Patented Mar. 28, WSG

FURNACE FRONT..WALL (JONSTRUCTIQN- FOR SPREADER STQKERS Earle C. Milieu Worcester, Mass, assignor-to Riley Stoker-Corporation, Worcester,- Mass., acorporation of Massachusetts Application November 15, 1946, Serial No. 710,162

(Cl. lit -4) 12 Claims.

This inventionrelates to furnace wall constructions, and more particularly to walls forfurnaces arranged to be fired by stokers of thewell-known spreader type.

Theusual spreaderstokerfurnace includes an upright metal front plate having an opening therein through which the fuel is projected rearwardly by the action ofrevolving rotorblades located in front of the opening; The fine particles of fuel burn in suspension, and the coarse particles are deposited upon agrate to form a fuel bed. In order topermit inspection of the fuel bed and the use of firing tools thereon when necessary, a fire door opening is provided in the front plate beneath the fuel'admission opening. A dead plate is usually provided between the grate and the fire dooropening.

In such a furnace itis important to protect the portion of the front plate between the two openings from the furnace heat and from the abrasive action of the entering fuel. It is also important to prevent fuel from being deposited in appreciable amountsonthe dead plate. Furthermore, the rotor and particularly the shaft por-- tion thereof should be shielded so far as possible from radiant heat. These facts have been recognized, and variousstructures have been mounted at the rear of the front plate, directly beneath the fuel admission opening, in attempts to solve the problem. However; these prior arrangements have been subject to difficulties in operation. Certain of these constructions have beeninca pable of withstanding the severeradiant heat-to which they are necessarily subjected. Other constructions have been readily worn away by the action of the enteringfuel, or readily damaged by accidental engagement of 'firingtocls therewith, or easily crackedby the effect-of cold air entering the furnace when the'fire, door-is opened.

It is accordingly oneobject of the invention to provide an improved wall construction for: use with'spreaderstokers, whereby the above-mam tioned difiiculties willbe avoided.

It is a further-object ofthe invention to provide a furnace wall construction including a metal front'plate having a fuel 'admission opening, and parts securedtoithe rearof the-front plate directly beneath the open'ing so constructed and'arranged as to protectzthev front" plate from thefurnace heat and from-abrasion oy. theentering fuel.

It is a further object. of'the;v invention to provide' a furnace wall of; simple and inexpensive construction, whichwwill withstand severeoperata ing conditions throughout a long: lifeof useful service. the various heat-exposedparts being-era ranged for easy replacement in a simple manner when required.

With these and other objects in view, as will be apparent to those skilled in the art; the invent tion resides in the combination-of parts setforth in the specification and 'covered bythe claims ape. pended hereto.

Referring to the drawings-illustrating one.em-. bodiment of the invention; and in which -like:ref'-. erence numerals indicate like parts,

Fig. 1 is a vertical. section through thefront wall of aspreader stoker; furnace, the section being taken on theline .l-l of Fig; 2.;

Fig. 2 is a section taken on the line Z72 of- Fig. 1;

Fig. 3' is a section taken onthe line 3-=$vof Fig; 1;

Fig. 4 is an enlargedview-of a-portion of Fig; 1;

Fig. 5 is a plan. view showing the detailed construction of a support bracket;

Fig. 6 is a rear elevation of the support bracket;

Fig. 7 is a section taken on the line-.l+-.-.1 of Fig. 6;

Fig. 8' is a perspective view. of a, refractory block;

Fig. 91s a perspective view. of "a retainer block; and

Fig. 10 is a perspective view of a. pipe support;

The embodiment illustrated comprises a spreader stoker furnace having a grate l5, dead plates IS in front 0f the grate, and upright-side walls l! on opposite Sid8S0ff"thB furnace. At the frontof the dead plates there is provided an upright metal front platel j'having twolaterally spaced rectangular openings 26 therethrough im-.- mediatelyabove the level of the grate and dead plates. These openings 2! are normallyclosed by fire: doors 2 I -mounted on thefront surfaceof the plate I9. The frontplate i9 is alsoprovided with two rectangular fuel-admission openings 23 which are located a short distance alcove the: re spective fire door openings-2i): The oppositesides of each openingZt are protected by upright plates Qtzof heat-resisting metal, and the upperedge ofeach opening is protected; by adeflector plate 25 of similar material. Upright piers: Zlof re.- fractorymaterial are supported on: thedead plates l6 and extend upwardly atopposite sides of the openings Hand 23. In-front of each fuel admission opening Z'Btthere :is mounted a spreader stoker mechanismincluding ahousing 29, a horizontal rotatableshaft. 3%] supported in the housing; and" blades or paddles 31! mounted on the shaft. The houslngisaslightlyloverlaps thelower edge of the opening 23 in the front plate and provides a narrow ledge 32 which extends horizontally across the full width of this opening. It will be understood that fuel, for example crushed coal, will be delivered to the revolving blades 3| in a well-known manner by a suitable feeding mechanism, and that the blades will throw the fuel rearwardly through the opening 23 for combustion partly in suspension and partly in a fuel bed on the grate [5.

The present invention provides a highly effective construction for protecting the portions of the front plate l3 beneath the fuel admission openings 23. For this purpose a horizontal bar 34 is mounted behind and close to the front plate at substantially the same height as the lower edges of the openings 23. This bar is supported by means of hangers 35 which are bolted to the front plate on opposite sides of the openings 23. Each hanger includes a hook 36 which extends rearwardly beneath the bar 34. These hangers are protected from the furnace heat by the intervening refractory material of the piers 21. The bar 34 is preferably made in the form of a pipe of circular cross section, through which cool ing water is circulated from a suitable source, such as the city water supply.

This pipe 34 serves as a support for a row of retainer blocks 38 at each opening 23, these blocks extending between the side plates 24. As best shown in Fig. 9, each block 38 is provided with a transverse groove 39 of semi-circular cross section in its lower surface, and with a depending tongue or flange 40 immediately behind this groove. The lower front corner of each block is notched to provide a downwardly facing shoulder 42. The upper surface 43 of the front portion of each block is substantially horizontal, and the upper surface 44 of the rear portion of the block is inclined downwardly and rearwardly. The two opposite vertical side faces of the block are parallel. As shown in Fig. 4, when the parts are assembled the concave surface of the groove 39 will engage the pipe 34, and the shoulder 42 will rest upon the ledge 32 on the housing 29. The blocks 38 are preferably made of a heat-resisting metal, such as a suitable cast iron alloy.

Supporting members 46 are mounted on the rear surface of the front plate l9 immediately above the fire door openings 20 and somewhat below the pipe 34. These members are L-shaped in cross section, with an upwardly extending vertical flange 41 and a rearwardly extending horizontal flange 48 forming a shelf. The vertical flange 41 is provided with openings 50 to receive bolts which fasten the member to the front plate. The horizontal flange 43 is provided on its upper surface and its rear edge with laterally spaced narrow ribs 53. Rows of openings 54 are provided through the flange 48 between the ribs 53 for the downward discharge of air, as will be explained hereinafter. The members 46 are rather short, and as shown in Figure 2 three of them are required to extend across each fire door opening 2!]. They are preferably made of a heat-resisting alloy similar to that used for the blocks 38.

The members 46 above each door opening 20 serve to support a row of blocks 56 which are preferably formed of a suitable refractory material, such as baked fire clay. As best shown in Figure 8, the upper surface 51 of each block 56 is inclined downwardly and rearwardly, and the upper and lower rear corners of the block are well rounded. The lower front corner of the block is provided with a transverse notch 68. A hookshaped portion 60 projects forwardly and upwardly from the front of the block to provide an upwardly-open transverse groove 6|. The two opposite vertical side faces of the block are parallel. At assembly, as shown in Fig. 4, the blocks 56 will rest on the supporting members 43 in positions spaced rearwardly from the plate IS, with the rear portions of the horizontal flanges 4B engaging the notches 58, and the lower ends of the tongues 40 on the retainer blocks 33 engaging the notches 6l behind the hooked portions 60. Thus the tongues 40 interlock with the hooked portions 60 to prevent rearward movement of the refractory blocks 56. The upper surfaces 51 of the refractory blocks 56 lie in substantially the same plane as the upper surfaces 44 of the retainer blocks 38. Preferably, a sheet 63 of asbestos or other heat insulating material is inserted between the front surfaces of the refractory blocks and the adjacent rear surfaces of the tongues 40;

The blocks 38 and 56, the front plate l9, and the members 46 enclose a transversely extending chamber 65 above each of the fire door openings 28. These chambers 65 are supplied with air, and for this purpose vertical ducts 66-43! are provided at the sides of the openings 28 to connect the ends of the chambers with the space beneath the grate I5 and the dead plates I 6. These ducts are located between the front plate l9 and the refractory piers 21, so that the piers shield the ducts from the furnace heat.

The operation of the invention will now be apparent from the above disclosure. The revolving blades Sl' will throw fuel rearwardly through the openings 23 to form a bed of burning fuel on the rate l5, and air for combustion will enter the space beneath the grate either by the natural draft of t e furnace or preferably from a suitable forced draft fan in known manner. The blocks 38 and 5'i will prevent the fuel from being de osited in any appreciable quantities on the d ad lates 16. Fuel particles which slide rearwardly along the upper surface of these blocks and drop over the rear edges of the blocks 56 will be picked up by the air stream which flows rearwardly beneath the blocks 56 from the openings 54 in the members 46. Air reaches these openings after flowing upwardly through the ducts 66-61 and thence along the chambers 65 in cooling relation to the various parts forming the walls thereof. The blocks 38, which are effectively cooled by their contact with the water pipe 38, protect the front plate I9 and the blocks 55 from the abrasive action of the rearwardly traveling fuel particles and shield the rotor 38-3! from the radiant heat of the furnace. Fire tools may be inserted through the fire door openings 20 for the purpose of working upon the fuel bed when required, and the metal parts 46 will shield the refractory blocks 56 from damage through accidental contact with such tools. The stream of comparatively hot air issuing from the openings 54 will flow rear-wardly beneath the blocks .56 and protect them against the chilling effect of cold air entering through the openings 28 when the doors 2| are opened, such chilling being particularly harmful to hot refractory material. The ribs 53 serve to reduce the transfer of heat from the blocks 56 to the metal parts 46, and the sheet 63 of insulating material serves to reduce the transfer of heat from the blocks 5'5 to the metal blocks 38. If it ever becomes necessary to replace the refractory blocks 56, they may 5 easilybeareleasedir for rearward1 withdrawal; by lifting the blocks.-;3 from ;the;pipe-3.i.

Having:v thus:described:v my invention; what I claim as new and .desiretosecuraby-Letters Patentiisz' 11 A wall, for arspreader. stoker: furnace come prising an;uprightr,.front;plate having an; opening for'the :admissionzof fuel to thByflllIldCi-Zrill a;rearwarddirection; a shelf. behind the plate and spaced 'below the opening; a block; of :refrace tory material supported onpthe' shelf, avhorizoirtal barrbehind the plate near the loweredge of the opening, and a retainer block supported on the bar, the retainer block therefractcryblock having portions whichz interlock to prevent :rearward-movement of therefractory block;

2'. A: wall for aspreaden stoker furnace comprising an upright front plate having an opening-for the admission of'fuel'to the furnacein a rearward direction, a shelf behind the plate-and spaced below the opening, a block of refractory material supported on the shelf, ahorizontal'wator-cooled pipe-behind the plate near thelower edge of'the opening, and a retainen'block-supportedon'the pipe'and having a groove-inits lower-surface to receive the pipe, the retainer block and-the refrectory block havingportions which interlockto prevent rearward movement of the refractory block.

3; A wall for'aspreader stoker furnace comprising an upright front plate having'an opening for the admission of fuel to the furnace in a rearward direction; a shelf behind the plate and spaced below the opening, a block of refractory material supported on the shelf and having an upwardly-open transverse roove, ahorizontal bar behind the plate near the lower edge'of the opening, anda retainer block supported on the bar and having a groove in its lower surface to receive the bar, the rear portion of theretainer block extending downwardly intothe transversegroovein the refractory block to prevent rearward movement of tbe retainerrb-l'ock 4.. A WalLfor a spreader stokenfurnacdcomprising an upright front plate having an opening for the admission of fuel to the furnace in a rearward direction, a shelf behind the plate and spaced below the opening, a block of refractory material supported on the shelf and having an upwardly projecting hook-shaped portion, a horizontal water-coo ed pipe beind the plate near the lower ed e of the opening, and a retainer block supported on the pipe and having a groove in its lo er surface to receive the pipe, the retainer block including a tongue which extends downwardly behind the pipe and into engagement with t e said hook-s a ed portion to prevent rearward movement of the refractory block.

5. A wall for a s reader stoker furnace comprising an upri ht front late having an opening for the admission of fuel to the furnace in a rearward direction, a shelf behind the plate and spaced below the opening, a block of refractory material supported on the shelf and having an upwardly projecting hook-shaped portion, the up er surface of the block being inclined downwardlv and rear ardly, a horizontal watercoo ed pipe behind the plate near the lower edge of the openin and a retainer block supported on the pipe and having a groove in its lo er surface to receive the pipe, the retainer block including a tongue which extends downwardly behind the pipe and into engagement with the said hook-shaped portion to prevent rearward movement of the refractory block, the retainer block having: azdownwardly and;- rearwardly' inclined upperwsurface in. substantially the same planesas thezupper surface of l the refractory block- 6. A wall foraa;spreader stoke furnace comprising :an; upright-front; plate having :anopening for: the admission of fuel to thefurnace ina rearward:,direction,,.a shelf behind: the plate.- and spaced below theopening, a block: of refractory material supportedon the shelf and'havingan upwardly-projecting hook-shaped portion, a-horie zontal water-cooled pipe behind the plate near the lower; edge of the opening, and aretainer block supported on thepipe andhavinga groove inyits lower surface toreceive the-pipe, therea tainer block including. a tongue which extends downwardly behind the pipeand into engagement with: the: said, hook shaped portion. to prevent rearward: movement of therefractory block, the frontxportionofv the retainer block being-located within-the fuel admissionppening'in position to protect the loweredgethereof'from radiant heat and; romyabrasion by; the entering fuel.

'7. A- wallfor. a spreader stokerf-urnace com-. prising an upright front plate having an opening for" the admission ofgfueltto the: furnace in. a rearward direction,ashelfrbehind the plate and spaced below the opening, a, block of refractory material sup-ported; on. the shelf and having; an upwardlyprojecting hookeshaped-portion, a horizontal water-cooled pipe behind the plate near the lower. edge of the opening,- a retainer block supported onthe pipe and'having a groove in itslower-surface to receive the pipe, the retainer block including a-;tonguewhich; extends downe wardly-behind the pipe and; into engagement with theisaid hook-shaped portion to prevent rear,- ward movement of the refractory-block, and heat insulating material-between the rear surface of the retainerblock: and the adjacent front surface of, therefractory block..

8,; A wall for, a spreader stokerfurnace come prising an, upright front plate having an opening for; the. admission of fuelto the furnace in a rearward direction, a; shelf behind the plate and spaced below the opening, a block of refractory material supported on the shelf and having an upwardly projecting hook-shaped portion, the refractory block having a notch in its lower front portion into which the shelf extends, a horizontal water-cooled pipe behind the plate near the lower edge of the opening, and a retainer block supported on the pipe and having a groove in its lower surface to receive the pipe, the retainer block including a tongue which extends downwardly behind the pine and into engagement with the said hook-sha ed portion to prevent rearward movement of the refractory block.

9. A wall for a spreader stoke furnace comprising an upright front plate having an opening for the a mission of fuel to the furnace in a rearward direction and a fire door opening spaced below the fuel admission opening, a horizontal member of L-shape in cross section located behind the plate above the fire door opening and spaced below the fuel admission opening, the said member inclu ing an upwardly extending vertical flange secured to the plate and a rearwardly extending horizontal flange forming a shelf, a row of refractory blocks supported on the shelf and shaped to provide upwardly projecting hookshaped portions, a horizontal water-cooled pipe behind the plate near the lower edge of the fuel admission opening, and a row of retainer blocks supported on the pipe and each having a groove in its lower surface to receive the pipe, the retalner blocks having tongues which extend downwardly behind the pipe and into engagement with the said hook-shaped portions to prevent rearward movement of the refractory blocks.

10. A wall for a spreader stoker furnace comprising an upright front plate having an opening for the admission of fuel to the furnace in a rearward direction and a fire door opening spaced below the fuel admission opening, a shelf behind the plate above the fire door opening and spaced below the fuel admission opening, a row of refractory blocks supported on the shelf and spaced rearwardly from the plate to provide a chamber, a horizontal bar behind the plate near the lower edge of the fuel-admission opening, a row of retainer blocks supported on the bar, the retainer blocks and the refractory blocks having portions which interlock to prevent rearward movement of the refractory blocks, and upright ducts behind the' plate on opposite sides of the fire door opening arranged to supply air to the ends of the chamber, the shelf having openings therein through which the air is discharged downwardly from the chamber.

11. A wall for a spreader stoker furnace comprising an upright front plate having an opening for the admission of fuel to the furnace in a rearward direction and a fire doo opening spaced below the fuel admission opening, a shelf behind the plate above the fire door opening and spaced below the fuel admission opening, a row of refractory blocks supported on the shelf and spaced rearwardly from the plate to provide a chamber, a horizontal ba behind the plate near the lower edge of the fuel-admission opening, a row of retainer blocks supported on the bar, the retainer blocks and the refractory blocks having portions which interlock to prevent rearward movement of the refractory blocks, upright ducts behind the plate on opposite sides of the fire door opening arranged to supply air to the ends of the chamber, the shelf having openings therein through which the air is discharged downwardly from the chamber, and upright piers of refractory material directly behind the ducts to protect them from the radiant heat of the furnace.

12. A wall for a spreader stoker furnace comprising an upright front plate having an opening for the admission of fuel to the furnace in a rearward direction and a fire door opening spaced below the fuel admission opening, a shelf behind the plate above the fire door opening and spaced below the fuel admission opening, a row of refractory blocks supported on the shelf and spaced rearwardly from the plate to provide a chamber, the refractory blocks having upwardly projecting hook-shaped portions, a horizontal water-cooled pipe behind the plate near the lower edge of the fuel admission opening, supporting means for the pipe secured to the rear surface of the plate, a row of retainer blocks supported on the pipe and each having a groove in its lower surface to receive the pipe, the retainer blocks having tongues which extend downwardly behind the pipe and into engagement with the said hook-shaped portions to prevent rearward movement of the refractory blocks, the front portions of the retainer blocks being located within the fuel admission opening in position to protect the lower edge thereof from radiant heat and from abrasion by the entering fuel, and upright ducts behind the plate on opposite sides of the fire door opening arranged to supply air to the ends of the chambers, the shelf having openings therein through which the air is discharged downwardly from the chamber.

EARLE C. MILLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

